The removal of sulfur compounds from petroleum streams has been of considerable importance in the past and is even more so today due to environmental considerations. Gas effluent from the combustion of organic materials, such as coal, almost always contain sulfur compounds and sulfur removal processes have concentrated on removing hydrogen sulfide since it has been considered a significant health hazard and also because it is corrosive, particularly when water is present. With increasing emphasis on eliminating or minimizing sulfur discharge to the atmosphere, attention is turning to the removal of other sulfur compounds from gas streams.
The removal of sulfur compounds and particularly chemically-combined sulfur, such as organosulfur compounds, from feedstreams is highly desirable to meet environmental concerns and to prevent potential catalyst deactivation as well as equipment corrosion.
Typically, hydrocarbon products contain various amounts of sulfur compounds in the form of, for example, chemically-combined sulfur, such as inorganically combined sulfur and organically combined sulfur, i.e., organosulfur compounds.
The presence of organosulfur compounds in hydrocarbon streams results naturally, as well as from the introduction of organosulfur compounds into the hydrogen streams during conventional processes for producing and treating hydrocarbon products.
As previously indicated, if chemically-combined sulfur, such as organosulfur compounds, are not removed from the hydrocarbon streams, the presence of organosulfur compounds in the resultant hydrocarbon products, including natural gas, paraffins, olefins and aromatics, particularly gasoline, diesel or other fuels, can cause corrosion of processing equipment and engine parts, as well as other deleterious effects, particularly when water is present.
Oxidative desulfurization research for diesel and other oil streams has been ongoing for over 100 years. The following table summarizes patents granted from 1941 to 1976 directed to oxidative desulfurization.
Patent No.InventorAssigneeTitle2,253,308Rosen,StandardDesulfurization of Aug. 19, 1941RaphaelCatalyticHydrocarbons2,697,682Porter,Anglo-Catalytic Desulfurization of Dec. 21, 1954FredrichIranian Oil Petroleum Hydrocarbons2,671,049Brown,Standard Odor Improvement of Mar. 2, 1954RussellOilPetroleum Oils2,834,717Shiah, ChynProcess of Desulfurizing May 13, 1958Hydrocarbons with a Boron Fluoride3,284,342Nathan,BritishDesulfurization of Nov. 8, 1966WilfredPetroleumHydrocarbon Materials3,341,448Ford, John BritishDesulfurization of Sep. 12, 1967PetroleumHydrocarbons Oxidative Hydro-Treatments3,565,793Herbstman, Texaco, Desulfurization With a Feb. 23, 1971SheldonInc.Catalytic Oxidation Step3,595,778Smetana,Texaco, Desulfurization Process Jul. 27, 1971RichardInc.Including an Oxidation Step3,719,589Herbstman,Texaco, Asphalt Separation in De-Mar. 6, 1973 SheldonInc.Sulfurization with an Oxidative Step3,816,301Sorgenti,AtlanticProcess for the Desulfurization Jun. 11, 1974HaroldRichfieldof Hydrocarbons3,945,914Yoo, JimAtlanticProcess of Sulfur Reduction Mar. 23, 1976Richfieldof an Oxidized Hydrocarbon
Paris-Marcano U.S. Pat. Nos. 5,017,280 and 5,087,350 disclose oxidative desulfurization of petroleum using nitric acid with hydrogen peroxide. Gore U.S. Pat. Nos. 6,274,785 and 6,160,193 disclose oxidative desulfurization Cabrerra U.S. Pat. No. 6,171,478 discloses a complex oxidative desulfurization patent. Rappas U.S. Pat. Nos. 6,402,940 and 6,406,616 disclose oxidative desulfurization using performic acid; and Ohsohl U.S. Pat. Nos. 5,985,137 and 5,948,242 disclose desulfurization of crude oil.
Jeanblanc PCT Patent Publication WO 00/15734 discloses radiative assisted oxidative desulfurization. Sulfur-containing carbonaceous materials are desulfurized by reaction with a mixture of an oxidizing agent and an oxygenated solvent such as diethyl ether under alkaline conditions at a temperature preferably ranging from ambient temperature to about 121° C. and pressure of about 1 to 2 atmospheres. The use of radiation—such as X-ray, infrared, visible microwave, or ultraviolet radiation, alpha, beta or gamma radiation, other atomic radiation emanating from a radioactive material, or ultrasound—facilitates desulfurization. The products of the reaction are a desulfurized carbonaceous material in which the sulfur content is (for example) less than about 1% and separated sulfur compounds.
Yen U.S. Pat. No. 6,402,939 discloses ultrasonic assisted oxidative desulfurization. Gunnerman U.S. Pat. Nos. 6,500,219 and 6,652,592 and Stowe U.S. Pat. No. 5,547,563 also disclose ultrasonic assisted oxidative desulfurization.
Cullen US Patent Publications 2004/0200759, 2004/0222131, 2004.0074812 and U.S. Pat. No. 7,081,196 disclose oxidative, reactive, ultrasonic desulfurization processes.
Collins U.S. Pat. Nos. 5,847,120 and 6,054,580 disclose tetraamidomacriocyclic ligand complexes of iron as homogeneous oxidation catalysts to promote peroxide oxidations. The complex provides a stable, long-lived oxidation catalyst or catalyst activator.
Kocal U.S. Pat. No. 6,277,271 discloses a process for the desulfurization of a hydrocarbonaceous oil in which hydrocarbonaceous oil and a recycle stream containing sulfur-oxidated compounds are contacted with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to reduce the sulfur level to a relatively low level. The resulting hydrocarbonaceous stream from the hydrodesulfurization zone is contacted with an oxidizing agent to convert the residual, low level of sulfur compounds into sulfur-oxidated compounds. The residual oxidizing agent is decomposed and the resulting hydrocarbonaceous oil stream containing the sulfur-oxidated compounds is separated to produce a stream containing the sulfur-oxidated compounds and a hydrocarbonaceous oil stream having a reduced concentration of sulfur-oxidated compounds. At least a portion of the sulfur-oxidated compounds is recycled to the hydrodesulfurization reaction zone.
Kocal U.S. Pat. No. 6,368,495 discloses removal of sulfur-containing compounds from liquid hydrocarbon streams using hydrogen peroxide and air, with heterogeneous transition metal catalysts. The process more specifically addresses the removal of thiophenes and thiophene derivatives from a number of petroleum fractions, including gasoline, diesel fuel, and kerosene. In the first step of the process, the liquid hydrocarbon is subjected to oxidation conditions in order to oxidize at least some of the thiophene compounds to sulfones. Then, these sulfones can be catalytically decomposed to hydrocarbons (e.g. hydroxybiphenyl) and volatile sulfur compounds (e.g., sulfur dioxide). The hydrocarbon decomposition products remain in the treated liquid as valuable blending components, while the volatile sulfur compounds are easily separable from the treated liquid using well-known techniques such as flash vaporization or distillation.
Cabrera U.S. Pat. No. 6,171,478 discloses desulfurization of a hydrocarbonaceous oil in which the oil is contacted with a hydrodesulfurization catalyst in a hydrodesulfurization reaction zone to reduce the sulfur level to a relatively low level and then contacting the resulting stream from the desulfurization zone with an oxidizing agent to convert the residual, low level of sulfur compounds into sulfur-oxidated compounds. The resulting oil stream containing the sulfur-oxidated compounds is separated after decomposing any residual oxidizing agent to produce a stream containing the sulfur-oxidated compounds and an oil stream having a reduced concentration of sulfur-oxidated compounds.
Shum U.S. Pat. No. 4,772,731 discloses the epoxidation of olefins with molybdenum dioxo dialkyleneglycolate compositions. Molybdenum dioxo dialkyleneglycolate compositions are produced by reaction of molybdenum trioxide with particular dialkylene glycol compounds at specified elevated temperatures while removing water. These compounds are described as being useful as catalysts in the epoxidation of olefinic compounds with an organic hydroperoxide.
Shum U.S. Pat. No. 5,780,655 discloses an epoxidation process using an alkylammonium phosphate-stabilized peroxotungstate compound as catalyst. Olefins are selectively converted to epoxides using hydrogen peroxide as oxidant in a single liquid phase reaction system characterized by a liquid phase comprised predominantly of an organic solvent. The reaction is catalyzed by a compound comprised of a phosphate-stabilized peroxotungstate species having a W:P atomic ratio of 2:1. This disclosure pertains to methods of converting olefins to epoxides in a single liquid phase using hydrogen peroxide and a catalyst in salt or acid form comprising a species corresponding to (R4N)2PW2O13(OH).
Venturello U.S. Pat. No. 5,274,140 discloses a process for olefin epoxidation by reaction with hydrogen peroxide according to a double phase technique (i.e., a biphasic reaction system containing both an aqueous phase and an organic phase). The catalyst system consists of a first component which is at least one element selected from W, Mo, V or a derivative thereof and a second component which is at least one derivative selected from the derivatives of P and As. The mutual atomic ratio of the catalyst components is between 12 and 0.1, but preferably is between 1.5 and 0.25.
Venturello U.S. Pat. Nos. 4,562,276 and 4,595,671 describe epoxidation catalysts for olefinic compounds, both in a homogeneous aqueous phase as well as in a heterogeneous phase. The catalysts correspond to the formula Q3 XW4O24−2n wherein Q represents a cation of an anionic salt, X is either P or As, while n=0, 1, or 2. The atomic ratio of W:P, where X=P, thus must be 4. The use of such compositions in an epoxidation wherein the reactants are maintained in a single substantially organic phase is not disclosed.
Bonsignore U.S. Pat. No. 5,324,849 discloses a class of compounds based on tungsten and diphosphonic acids which contain active oxygen atoms and cationic groups derived from onium salts. Such compounds are said to catalyze olefin oxidation reactions in double phase reaction systems containing both an organic phase and an aqueous phase. The compounds contain two phosphorus atoms and five tungsten atoms and thus have a W:P atomic ratio of 5:2.
However, the biphasic reaction systems of the type described in the aforementioned patents have a number of disadvantages which limit their usefulness in large scale commercial practice. Thus, there is a need to develop active catalysts capable of providing high selectivity to organosulfur compounds during oxidative desulfurization processes.